A great deal of Clemens's socializing took place at dinners and events at private clubs; he was completely at ease within the club life of New York City and London. In New York he mingled with the literary and journalism crowd at the Lotos Club, the theatrical world at the Players Club, and the artists of the Tile Club. In London he frequented the Whitefriars Club, the Savage Club, and the Pilgrims Club, among others.
He also happily found time for more modest local organizations, like Hartford's Saturday Morning Club, a young ladies' social and cultural group that met occasionally at the Clemens home, and the Monday Evening Club, a rather earnest and philosophical discussion group of his male cronies.
In addition, Clemens created a number of idiosyncratic clubs of his own, like the Modest Club, of which he was the only member; the Damned Human Race Club, whose four members never managed to convene; the Juggernaut Club, an international group made up of girls and women with whom he corresponded; and the Aquarium, his club of young girls, or "Angelfish," whom he considered his surrogate grandchildren.